phase change materials have a high capacity in thermal energy storage, these materials can be used to prevent the heat transfer into the building besides optimize and improve the performance of the refrigeration and air conditioning system. Adding phase change materials (PCM) to the building can improve the inside comfort temperature and save consumption energy of the building. In this article the parameters that affect the performance of PCM in the building walls, such as phase change temperature, latent heat, thickness, thermal conductivity, etc., have been investigated using ANSYS software. the numerical simulation of thermal energy storage in the solar walls of the building have investigated using phase change materials in different thicknesses with different heat flux rates. This wall is designed to capture the sun energy during the day, reducing energy consumption and optimizing it during peak times. Manuscript profile